Question: Simplify the following expression: $ r = \dfrac{9z + 5}{-2} + \dfrac{-3}{10} $
In order to add expressions, they must have a common denominator. Multiply the first expression by $\dfrac{10}{10}$ $ \dfrac{9z + 5}{-2} \times \dfrac{10}{10} = \dfrac{90z + 50}{-20} $ Multiply the second expression by $\dfrac{-2}{-2}$ $ \dfrac{-3}{10} \times \dfrac{-2}{-2} = \dfrac{6}{-20} $ Therefore $ r = \dfrac{90z + 50}{-20} + \dfrac{6}{-20} $ Now the expressions have the same denominator we can simply add the numerators: $r = \dfrac{90z + 50 + 6}{-20} $ $r = \dfrac{90z + 56}{-20}$ Simplify the expression by dividing the numerator and denominator by -2: $r = \dfrac{-45z - 28}{10}$